drawing straight to an in-code bitmap?

[Desolator144]

I can't seem to figure out how to draw a gradient to a bitmap I created in code. I have the background fading with a crazy bouncing sort of gradient with this code (paste it into a project if U wanna see it )

Dim m_intAntiBlueC1 As Integer = 255
    Dim m_intAntiBlueC2 As Integer = 0
    Dim m_blnC1GoUp As Boolean
 
Dim graphics As Graphics
        graphics = Me.CreateGraphics()
        Dim c1 As Color = Color.FromArgb(m_intAntiBlueC1, m_intAntiBlueC1, 200)
        Dim c2 As Color = Color.FromArgb(m_intAntiBlueC2, m_intAntiBlueC2, 200)
        Dim brush As New Drawing2D.LinearGradientBrush(Me.DisplayRectangle, c1, c2, Drawing2D.LinearGradientMode.ForwardDiagonal)
        graphics.FillRectangle(brush, Me.DisplayRectangle)
[COLOR=Red]        Dim TheBit As New Bitmap(295, 80)
        Dim graphics2 As Graphics[/COLOR]
 
        If m_intAntiBlueC1 = 255 Then
            m_blnC1GoUp = False
        ElseIf m_intAntiBlueC1 = 0 Then
            m_blnC1GoUp = True
        End If
 
        If m_blnC1GoUp Then
            m_intAntiBlueC1 += 1
            m_intAntiBlueC2 -= 1
        Else
            m_intAntiBlueC1 -= 1
            m_intAntiBlueC2 += 1
        End If

I can't seem to create a graphics area from the bitmap itself so I don't know any other way to draw graphics data onto the bitmap. Anyone know how to do it?

[kleinma]

graphics = Me.CreateGraphics() creates a graphics object for the canvas of the object specified (Me, aka the form)

Bitmaps don't have a canvas to draw on.. they are simply a collection of bytes that make up the image.

You could load the bitmap into a picturebox, draw on the picturebox canvas, and then save the picturebox to file...

[Desolator144]

I just added some code through the wonderful logic of creating a new object every time it asked for one without fully knowing what the object is :P

Dim TheBit As New Bitmap(295, 80)
        Dim graphics2 As Graphics
        Dim IntPtr As IntPtr
        IntPtr = TheBit.GetHbitmap()
        graphics2 = Drawing.Graphics.FromHwnd(IntPtr)
        Dim rect As New RectangleF()
        rect = graphics2.VisibleClipBounds
        graphics2.FillRectangle(brush, rect)

but it stops at the graphics2 = Drawing.Graphics.FromHwnd(IntPtr) line and gives me an error that simply says "out of memory" and that's it. I'm gonna ask my teacher tonight to teach us about handles and pointers and all that crap for like the millionth time grrrrrrrrrr

[Desolator144]

yeah I know doing it with a picturebox would be super simple but I eventually want to assign the bitmap to the background image on a label control, effectively making a really cool moving background. I think I'll just stick a picturebox under the label and make it transparent

[VBDT]

this is one of the ways to do it

Dim bmp As New Bitmap(Width, Height)
        Dim g As Graphics
        g = Graphics.FromImage(bmp)
 
        'use the g to draw any thing
 
        'dispose the graphics object.
        g.Dispose()

[Desolator144]

well, that didn't work. I set the backcolor to transparent and it still shows up as control gray or whatever. That's never happened before, what's up with that?

[VBDT]

I am not sure what you are doing but using your code i get this.

Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        Dim bmp As New Bitmap(295, 80)
        Dim g As Graphics
        g = Drawing.Graphics.FromImage(bmp)
 
        Dim m_intAntiBlueC1 As Integer = 255
        Dim m_intAntiBlueC2 As Integer = 0
        Dim m_blnC1GoUp As Boolean
        Dim c1 As Color = Color.FromArgb(m_intAntiBlueC1, m_intAntiBlueC1, 200)
        Dim c2 As Color = Color.FromArgb(m_intAntiBlueC2, m_intAntiBlueC2, 200)
        Dim brush As New Drawing2D.LinearGradientBrush(Me.DisplayRectangle, c1, c2, Drawing2D.LinearGradientMode.ForwardDiagonal)
        g.FillRectangle(brush, Me.DisplayRectangle)
       
        If m_intAntiBlueC1 = 255 Then
            m_blnC1GoUp = False
        ElseIf m_intAntiBlueC1 = 0 Then
            m_blnC1GoUp = True
        End If
 
        If m_blnC1GoUp Then
            m_intAntiBlueC1 += 1
            m_intAntiBlueC2 -= 1
        Else
            m_intAntiBlueC1 -= 1
            m_intAntiBlueC2 += 1
        End If
        brush.Dispose()
        g.Dispose()
        Me.PictureBox1.Image = bmp
 
    End Sub

[Desolator144]

uh oh, post delay :P that one above my last one worked w00t. Why did they have to hide FromImage so well? geeeeeeeeeeze. But for some odd reason when I do TheLabel.Image = TheBitmap, it renders correctly on the left but not on the right. It's like it's overflowing even though I double checked and the label and bitmap and graphics area are all drawing to the correct size. I'll post a video or gif of it when I get home :P
Okay nm here's screenshots :P here's the important parts of code having to do with size:

Dim TheBit As New Bitmap(295, 80)
graphics2 = Drawing.Graphics.FromImage(TheBit)
graphics2.FillRectangle(brush, 0, 0, 295, 80)

and yet, here's one "peak" and the other "peak" of the gradient cycle from 0-255. According to Pixie, it only reaches about 33 on one peak and 86 on the other, suggesting the gradient bitmap doesn't fit in the area, except the label really is 295x80. Like on the 2nd peak here, it should be 100% purple on the right and on the first one it should be close to 100% yellow on the left but they're WAY off



Here's the actual, complete code if U wanna try it:

'module lvl:
    Dim m_intAntiBlueC1 As Integer = 255
 
'timer tick sub:
        If m_intAntiBlueC1 >= 255 Then
            m_blnC1GoUp = False
        ElseIf m_intAntiBlueC1 <= 0 Then
            m_blnC1GoUp = True
        End If
 
        If m_blnC1GoUp Then
            m_intAntiBlueC1 += 3
 
        Else
            m_intAntiBlueC1 -= 3
 
        End If
 
        Dim graphics As Graphics
        graphics = Me.CreateGraphics()
        Dim c1 As Color = Color.FromArgb(m_intAntiBlueC1, m_intAntiBlueC1, 200)
        Dim c2 As Color = Color.FromArgb(255 - m_intAntiBlueC1, 255 - m_intAntiBlueC1, 200)
        Dim brush As New Drawing2D.LinearGradientBrush(Me.DisplayRectangle, c1, c2, Drawing2D.LinearGradientMode.ForwardDiagonal)
        graphics.FillRectangle(brush, Me.DisplayRectangle)
        Dim TheBit As New Bitmap(295, 80)
        Dim graphics2 As Graphics
        graphics2 = Drawing.Graphics.FromImage(TheBit)
 
 
        c1 = Color.FromArgb(255, m_intAntiBlueC1, 200)
        c2 = Color.FromArgb(255, 255 - m_intAntiBlueC1, 200)
        brush = New Drawing2D.LinearGradientBrush(Me.DisplayRectangle, c1, c2, Drawing2D.LinearGradientMode.Horizontal)
        graphics2.FillRectangle(brush, 0, 0, 295, 80)
        lblLogo.Image = TheBit

[Desolator144]

OMG
I just realized I was using the form's display rectangle in the redeclaration of the brush! AHHHHHHHHHHHH!!!!!!!!!!!!!!!
Here's the real real real real real REAL code if U wanna see the absolute beautiful awesome!

If m_intAntiBlueC1 >= 255 Then
            m_blnC1GoUp = False
        ElseIf m_intAntiBlueC1 <= 0 Then
            m_blnC1GoUp = True
        End If
 
        If m_blnC1GoUp Then
            m_intAntiBlueC1 += 3
        Else
            m_intAntiBlueC1 -= 3
        End If
 
        Dim graphics As Graphics
        graphics = Me.CreateGraphics()
        Dim c1 As Color = Color.FromArgb(m_intAntiBlueC1, m_intAntiBlueC1, 200)
        Dim c2 As Color = Color.FromArgb(255 - m_intAntiBlueC1, 255 - m_intAntiBlueC1, 200)
        Dim brush As New Drawing2D.LinearGradientBrush(Me.DisplayRectangle, c1, c2, Drawing2D.LinearGradientMode.ForwardDiagonal)
        graphics.FillRectangle(brush, Me.DisplayRectangle)
        Dim TheBit As New Bitmap(295, 80)
        Dim graphics2 As Graphics
        graphics2 = Drawing.Graphics.FromImage(TheBit)
 
        
        'txtDebug.Text = txtDebug.Text & vbNewLine & c1.R.ToString & "," & c1.G.ToString & "," & c1.B.ToString & "   " & c2.R.ToString & "," & c2.G.ToString & "," & c2.B.ToString
       
        brush = New Drawing2D.LinearGradientBrush(lblLogo.DisplayRectangle, c1, c2, Drawing2D.LinearGradientMode.Horizontal)
        graphics2.FillRectangle(brush, 0, 0, 295, 80)
        lblLogo.Image = TheBit
 
        'If m_intAntiBlueC1 = 0 Then
        '    tmrGradient.Enabled = False
        '    'TheBit.Save("peak2.bmp")
        'End If

and declare the module rgb variables at module lvl